Solid state imaging device and method for manufacturing the same

ABSTRACT

A solid state imaging device includes: a solid state imaging element including a light receiving element, a microlens formed above the light receiving element, a first transparent layer formed on the microlens and a second transparent layer formed on or above the microlens and harder than the first transparent layer; a transparent component formed above the second transparent layer; and an adhesive layer for bonding the second transparent layer and the transparent component. The hard second transparent layer prevents the occurrence of scratches during a dicing step.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a solid state imaging device providedwith a transparent component such as glass bonded to a light receivingsurface and a method for manufacturing the same.

2. Description of Related Art

A known solid state imaging device using a CCD (charge coupled device)is provided with a solid state imaging element including a photodiode asa light receiving element and a microlens provided above it and atransparent component such as glass for protecting the solid stateimaging element.

FIGS. 6A and 6B are sectional views illustrating the structure of aconventional solid state imaging device. In the conventional solid stateimaging device, as shown in FIG. 6A, recesses are formed in the topsurface of a substrate 101 for forming CCD solid state imaging elementson a subpixel-by-subpixel basis and photodiodes 102 for convertingincident light 111 into an electronic signal are provided at the bottomof the recesses, respectively. A first acrylic planarization film 103 isformed on the substrate 101 to make the uneven top surface of thesubstrate flat. Color filters 104 are formed on the first acrylicplanarization film 103 in one-to-one relationship with the photodiodes102. A second acrylic planarization film 105 is formed on the colorfilters 104 to bury the unevenness caused by the color filters 104 andthe gaps therebetween. Further, microlenses 106 are formed on the secondacrylic planarization film 105 in one-to-one relationship with thephotodiodes 102.

As shown in FIG. 6B, a solid state imaging element 113 including thephotodiodes 102, color filters 104 and microlenses 106 formed on thesubstrate 101 is placed in a package 112 and the top of the package 112is covered with a transparent component 109. An air layer (space) 110exists in the package 112 between the solid state imaging element 113and the back surface of the transparent component 109 as shown in FIGS.6A and 6B. Referring to FIG. 6A, the light 111 passes through thetransparent component 109 to enter the microlenses 106 and at the sametime, reflection occurs on the top and back surfaces of the transparentcomponent 109 and the top surfaces of the microlenses 106. In theconventional solid state imaging device, sufficient sensitivity has beenobtained with the light transmitted to the photodiodes 102 only.However, according to finer design rules of the solid state imagingdevice adopted in recent years, it has been getting more difficult toobtain satisfactory sensitivity only with the light collected by themicrolenses. As a solution to this, Japanese Patent No. 2719238 proposesa structure having an anti-reflection film formed on the microlenses.

SUMMARY OF THE INVENTION

The conventional solid state imaging device is disadvantageous in thatthe degree of reflection at the interface between the air layer 110 andthe transparent component is high and dust trapped in the package duringtransfer may possibly move to an imaging region.

To eliminate the disadvantages, the inventors of the present inventionhave made a close study of the structure of the device and hit upon anidea of applying a transparent component directly to a transparent resinlayer formed to cover the microlenses 106 (see FIG. 6A). With such astructure, the solid state imaging device is not affected by the dustand the like because the air layer 110 is eliminated by the transparentresin layer. If the transparent resin layer is made of afluorine-containing resin having a lower refractive index than that ofthe microlenses 106, light transmitted through the microlenses 106 issurely collected on the photodiodes 102. Further, the refractive indexof the transparent resin layer can be set to an intermediate valuebetween the refractive index of the transparent component 109 and thatof the microlenses 106. Therefore, the difference between the refractiveindices of the transparent component 109 and the transparent resin layeris reduced, and so is the difference between the refractive indices ofthe microlenses 106 and the transparent resin layer. Thus, reflection oflight at the interfaces between them is reduced.

However, if the transparent resin layer is made of a fluorine-containingresin having a low refractive index to reduce the reflection of theincident light, a scratch may possibly occur on the top surface of animaging region of the solid state imaging element in the step of cuttingthe wafer to separate the solid state imaging elements. The scratch onthe top surface of the transparent resin layer causes a black scratch inthe resulting image.

In light of the above, the present invention provides a small-sized andhigh-sensitivity solid state imaging device which is manufactured withhigh yield and a method for manufacturing the same.

A solid state imaging device according to a first aspect of the presentinvention includes a solid state imaging element including a lightreceiving element, a microlens formed above the light receiving element,a first transparent layer formed on the microlens and a secondtransparent layer formed on or above the microlens and harder than thefirst transparent layer; a transparent component formed above the secondtransparent layer; and an adhesive layer for bonding the secondtransparent layer and the transparent component.

With this structure, the second transparent layer is less likely to bedamaged by dust in the dicing step and the solid state imaging deviceaccording to the first aspect of the present invention is manufacturedwith high yield. Further, since there is no air layer between thetransparent component and the second transparent layer, the mixing ofdust between the transparent component and the microlens is less likelyto occur.

In particular, even if the first transparent layer has a lowerrefractive index than the microlens and is made of a softfluorine-containing resin, the presence of the second transparent layerreduces the occurrence of damage during the dicing step. As a result,incident light is effectively collected on the light receiving element.Thus, the solid state imaging device according to the first aspect ofthe present invention is provided with high sensitivity and small sizeand manufactured with high yield.

Examples of material for the second transparent layer include an acrylicresin, a styrene resin, an epoxy resin and PVA (polyvinyl alcohol) whichare free from fluorine. If the second transparent layer is made ofmaterial more hydrophilic than the first transparent layer, the dustgenerated during the dicing step is easily removed, thereby improvingthe manufacturing yield to a further extent.

The second transparent layer may have a refractive index of about 1.3 ormore and 1.6 or less such that the refractive index of the secondtransparent layer comes between the refractive indices of the firsttransparent layer and the adhesive layer even when the first transparentlayer and the adhesive layer are made of general materials. Accordingly,reflectance at the interfaces between these layers is reduced, therebymaking it possible to collect a sufficient amount of light on the lightreceiving element.

A solid state imaging device according to a second aspect of the presentinvention includes a solid state imaging element including a lightreceiving element, a microlens formed above the light receiving element,a first transparent layer formed on the microlens and a secondtransparent layer formed on or above the microlens and made of materialwhich is more hydrophilic than the first transparent layer; atransparent component formed above the second transparent layer; and anadhesive layer for bonding the second transparent layer and thetransparent component.

Since the second transparent layer is more hydrophilic than the firsttransparent layer, abatement generated during the dicing step is moreeasily washed away than the case where the second transparent layer isnot provided. Therefore, the solid state imaging device according to thesecond aspect of the present invention is manufactured with high yield.

A method for manufacturing the solid state imaging device according tothe first aspect of the present invention includes the steps of: (a)preparing a substrate in the form of a wafer having a light receivingelement for converting incident light into an electronic signal and amicrolens provided above the light receiving element to collect incidentlight on the light receiving element; (b) forming a first transparentlayer to cover at least the top surface of the microlens; (c) forming asecond transparent layer harder than the first transparent layer on thefirst transparent layer; and (d) cutting the wafer-shaped substrate intochips with the top surface of the second transparent layer exposed.

As the second transparent layer is harder than the first transparentlayer, scratches caused by the abatement are less likely to occur ascompared with the case where the second transparent layer is not formedin the step (d).

A method for manufacturing the solid state imaging device according tothe second aspect of the present invention includes the steps of: (a)preparing a substrate in the form of a wafer having a light receivingelement for converting incident light into an electronic signal and amicrolens provided above the light receiving element to collect incidentlight on the light receiving element; (b) forming a first transparentlayer to cover at least the top surface of the microlens; (c) forming asecond transparent layer made of material which is more hydrophilic thanthe first transparent layer on the first transparent layer; and (d)cutting the wafer-shaped substrate into chips with the top surface ofthe second transparent layer exposed and water supplied.

According to the method, the step (d) (dicing) is carried out with thehighly hydrophilic second transparent layer exposed. Therefore, the dustgenerated by cutting the substrate is easily washed away from thesubstrate surface.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is an oblique view illustrating the appearance of a solid stateimaging device according to a first embodiment of the present invention,

FIG. 1B is a top view of the solid state imaging device and

FIG. 1C is a sectional view illustrating part of an imaging region ofthe solid state imaging device.

FIGS. 2A to 2D are views illustrating the outline of a method formanufacturing the solid state imaging device of the first embodiment.

FIGS. 3A to 3G are sectional views illustrating the method formanufacturing the solid state imaging device of the first embodiment.

FIGS. 4A to 4F are plan views and sectional views illustrating the stepsof the method for manufacturing the solid state imaging device of thefirst embodiment after the dicing step.

FIG. 5A is an oblique view illustrating the appearance of a solid stateimaging device according to a second embodiment of the presentinvention,

FIG. 5B is a top view of the solid state imaging device and

FIG. 5C is a sectional view illustrating part of an imaging region ofthe solid state imaging device.

FIGS. 6A and 6B are sectional views illustrating the structure of aconventional solid state imaging device.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, detailed explanation of embodiments of the presentinvention is provided with reference to the drawings.

First Embodiment Structure of Solid State Imaging Device

FIG. 1A is an oblique view illustrating the appearance of a solid stateimaging device according to a first embodiment of the present invention,FIG. 1B is a top view of the solid state imaging device and FIG. 1C is asectional view illustrating part of an imaging region of the solid stateimaging device.

As shown in FIG. 1A, a solid state imaging device 36 of the presentembodiment includes a package 26 carrying a solid state imaging element20 therein and external terminals 32 for externally transmitting imagesignals. The solid state imaging element 20 is provided with an imagingregion 24 (a shaded portion in FIG. 1B) where light is received.

As shown in FIGS. 1B and 1C, the solid state imaging device 36 of thepresent embodiment further includes a transparent component 9 made ofglass, for example, which is bonded above the solid state imagingelement 20 with an adhesive layer 10. The package 26 is provided withterminals 22 electrically connected to the periphery of the imagingregion 24 of the solid state imaging element 20 via wires (connectors)28 and also to the external terminals 32.

The solid state imaging element 20 includes: a substrate 1 for formingCCD solid state imaging elements in which recesses are formed in theimaging region on a subpixel-by-subpixel basis; photodiodes (lightreceiving elements) 2 disposed at the bottom of the recesses to convertincident light into an electronic signal, respectively; a firstplanarization film 3 formed on the substrate 1 and the photodiodes 2 tomake the top surface of the substrate 1 flat; color filters 4 formed onparts of the first planarization film 3 above the photodiodes 2; asecond planarization film 5 formed to cover the color filters 4 toeliminate unevenness caused by the color filters 4; microlenses 6 formedon parts of the second planarization film 5 above the photodiodes 2; afirst transparent layer 7 formed on the microlenses 6 to bury at leastthe microlenses 6; and a second transparent layer 8 formed on the firsttransparent layer 7 and harder than the first transparent layer 7. Atransparent component 9 made of a glass plate is bonded onto the secondtransparent layer 8 with an adhesive layer 10. In FIG. 1C, the topsurface of the first transparent layer 7 is depicted as flat and smooth.However, the top surface of the first transparent layer 7 may be maderough to some extent by oxygen plasma treatment or the like to improvethe degree of adhesion between the first and second transparent layer 7and 8.

Among the above-described components, the first and second planarizationfilms 3 and 5 are transparent and may be made of an acrylic resin. Themicrolenses 6 are preferably transparent. In the present embodiment,however, the microlenses 6 are made of a positive photosensitive resinhaving naphthoquinonediazido as a photosensitive group. The transparentcomponent 9 may be made of a transparent resin in place of glass.

The first transparent layer 7 is made of a resin containing fluorine inits molecular structure (i.e., fluorine-containing resin). The secondtransparent layer 8 may be made of a resin having higher hardness thanthe fluorine-containing resin. The provision of the second transparentlayer 8 harder than the first transparent layer 7 between the firsttransparent layer 7 and the adhesive layer 10 is a characteristicfeature of the solid state imaging device of the present embodiment. Thehardnesses of the resins are easily compared using a commerciallyavailable hardness meter such as Nanoindenter. Examples of the materialfor the first transparent layer 7 include a fluorinated acrylic resinand a fluorinated silicone resin. Examples of the material for thesecond transparent layer 8 include an acrylic resin, a styrene resin, anepoxy resin and PVA (polyvinyl alcohol). The fluorinated resin issuitable as the material for the first transparent layer 7 because it istransparent and relatively soft and has a refractive index lower thanthat of the microlenses 6. Due to the refractive index lower than thatof the microlenses 6, light passing through the microlenses 6 issufficiently collected on the photodiodes 2. Further, the soft firsttransparent layer 7 absorbs stress to be applied to the components ofthe solid state imaging device after the transparent component 9 isadhered, thereby reducing the occurrence of failures. Moreover, as thehardness of the second transparent layer 8 is set higher than that ofthe first transparent layer 7, scratches are less likely to occur on thetop surface of the solid state imaging element during the manufacture.

In the solid state imaging device of the present embodiment, therefractive indices of the microlenses 6, first transparent layer 7,second transparent layer 8, adhesive layer 8 and transparent component 9are about 1.55 to 2.0, about 1.3 to 1.5, about 1.3 to 1.6, about 1.5 to1.6 and about 1.55 or higher, respectively.

The components vary in thickness. For example, the thickness of each ofthe microlenses 6 may be about 0.3 μm or more and 2.0 μm or less. Thefirst transparent layer 7 may have enough thickness to cover at leastthe top surfaces of the microlenses 6, for example, about 0.1 μm or moreand 2.0 μm or less. The thickness of the second transparent layer 8 isabout 0.05 μm or more and 2.0 μm or less. The thickness of the adhesivelayer 10 may be about 0.05 μm or more and 10 μm or less. Although thefirst and second transparent layers 7 and 8 are depicted to have flatand smooth top surfaces in FIG. 3F, the first transparent layer 7 mayhave unevenness on the top surface derived from the configuration of themicrolenses 6 and the top surface of the second transparent layer 8 maybe flat and smooth.

In the thus-configured solid state imaging device of the presentembodiment, light from outside passes through the transparent component9, adhesive layer 10, second transparent layer 8 and first transparentlayer 7 in this order, and then collected on the photodiodes 2 throughthe microlenses 6. The light is converted into an electronic signal inthe photodiodes 2 and sent to the periphery of the substrate 1 via a CCDcircuit, and then to the external terminals 32 via the wires 28 and theterminals 22.

Method for Manufacturing Solid State Imaging Device

Hereinafter, explanation of a method for manufacturing the solid stateimaging device of the present embodiment is provided.

FIGS. 2A to 2D are views illustrating the outline of the method formanufacturing the solid state imaging device of the present embodiment.As shown in FIGS. 2A and 2B, a semiconductor substrate made of siliconin the form of a wafer (hereinafter referred to as a substrate 1 forforming solid state imaging elements) is prepared and solid stateimaging elements are formed thereon. Then, as shown in FIG. 2C, thesubstrate 1 is cut to separate the solid state imaging elements whilewater and carbon dioxide are supplied. In this stage, the secondtransparent layer 8 exists at the topmost surface of the substrate 1.Each of the separated solid state imaging elements 20 is disposed in apackage (not shown) having a lead frame and assembled into a solid stateimaging device as a final product.

Now, detailed explanation of the steps shown in FIGS. 2A to 2D isprovided below.

FIGS. 3A to 3G are sectional views illustrating the method formanufacturing the solid state imaging device of the present embodimentand FIGS. 4A to 4F are plan views and sectional views illustrating thesteps of the method for manufacturing the solid state imaging device ofthe present embodiment after the dicing step. FIGS. 3A to 3G show partof an imaging region of the solid state imaging device. FIGS. 4B to 4Fare sectional views corresponding to FIGS. 4A to 4E and taken along aline passing through the terminals 22 arranged on both sides of thesolid state imaging element 20.

First, as shown in FIG. 3A, an acrylic resin is applied to the uneventop surface of the substrate 1 where the photodiodes 2 are arranged on apixel-by-pixel basis while the substrate 1 is rotated. Then, the appliedresin is dried by heating at about 180 to 250° C. for about 60 to 600seconds to form a first planarization film 3.

Then, as shown in FIG. 3B, color filters 4 are formed on parts of thefirst planarization film 3 above the photodiodes 2.

Then, as shown in FIG. 3C, an acrylic resin is applied to the entiresurface of the substrate 1 while the substrate 1 is rotated to removethe unevenness cased by the color filters 4. Then, the applied resin isdried by heating at about 180 to 250° C. for about 60 to 600 seconds. Inthe present embodiment, the application step and the drying step arerepeated about 2 to 8 times to obtain a highly smooth secondplanarization film 5.

Then, as shown in FIG. 3D, a styrene-based positive photosensitiveresist is applied to the entire surface of the second planarization film5 up to a thickness of 0.5 μm or more while rotating the substrate 1 anddried at a low temperature of about 90 to 110° C. for about 30 to 90seconds. Then, for example, the applied resist is selectively irradiatedwith i-rays at exposure energy of 100 to 1000 mJ, followed bydevelopment using a TMAH (tetramethyl ammonium hydroxide) solution.Thus, a desired pattern is formed by the remaining resist. Further, theremaining resist and the second planarization film 5 are irradiated withg-rays or other rays having a shorter wavelength than the g-rays atexposure energy of 200 mJ or higher to improve the transmittance of theremaining resist to visible light up to 80% or higher. Then, theremaining resist is heated at a moderate temperature of about 130 to220° C. for about 60 to 300 seconds. Thus, thermoplastic andthermosetting properties of the remaining resist are both controlled,thereby providing microlenses 6 having a top surface with a desiredcurvature and a desired refractive index. If the microlenses 6 areheated at a high temperature of about 190 to 280° C. for about 60 to 600seconds, the microlenses 6 improve in reliability, more specifically,resistance to heat and resistance to solvent (less likely to bedeteriorated by the solvent).

Then, as shown in FIG. 3E, a fluorine-containing resin is applied to theentire surface of the second planarization film 5 on which themicrolenses 6 have been formed up to a desired thickness of 0.1 μm ormore while rotating the substrate 1. The application of the resin iscarried out at about 500 to 5000 rpm (rotation per minute) such that thetop surface of the applied resin is not curved along the curved surfacesof the microlenses 6. Then, in order to avoid bumping of a solvent whichmay cause mixing of air bubbles in the fluorine-containing resin, theresin is dried at a low temperature of about 90 to 120° C. for about 60to 600 seconds. Then, the fluorine-containing resin is dried by heatingat about 150 to 250° C. for about 60 to 600 seconds to cure the resin,thereby forming a first transparent layer 7 having a desired refractiveindex. If the air bubbles are not likely to be mixed in the resin, thedrying step at a low temperature (90 to 120° C.) may be omitted. Thefluorine-containing resin may be cured by UV irradiation. In the presentembodiment, the first transparent layer 7 may be made of an acrylicresin, an olefin resin or a silicone resin. However, from the viewpointof heat resistance, a fluorine-containing silicone resin is preferablyused. The top surface of the resulting first transparent layer 7 may besubjected to plasma treatment using oxygen-containing gas.

Then, as shown in FIG. 3F, a resin material harder than the firsttransparent layer 7 is applied to the top surface of the firsttransparent layer 7 up to a desired thickness of 0.05 μm or more to 1.0μm or less while rotating the substrate 1. The resin harder than thefirst transparent layer 7 may be an acrylic resin, a styrene resin, anepoxy resin or PVA. During the resin application, the substrate 1 may berotated at 500 to 5000 rpm, for example. Then, the resin is dried byheating at about 150 to 250° C. for about 60 to 600 seconds, therebycuring the resin to form a second transparent layer 8. FIG. 3Fcorresponds to FIG. 2B.

Then, as shown in FIG. 2C, the substrate 1 is cut into chips using adicing saw while water is supplied onto the top surface thereof, therebyseparating the solid state imaging elements 20 (dicing step). In thisstep, since the hard second transparent layer 8 is exposed at thetopmost surface of the solid state imaging elements, damage to the topsurfaces of the elements derived from abatement (dust) is reduced ascompared with the case where the first transparent layer 7 is exposed atthe top. Therefore, the solid state imaging device of the presentembodiment is manufactured with higher yield than the solid stateimaging device not including the second transparent layer 8.

Then, as shown in FIGS. 4A and 4B, each of the separated solid stateimaging elements 20 is disposed in a package 26 having terminals 22. Forexample, in FIG. 4A, groups of terminals 22 are provided along the longsides of the solid state imaging element 20, respectively. The secondtransparent layer 8 is provided to cover the whole surface of thesubstrate 1 including an imaging region 24.

As shown in FIGS. 4C and 4D, wires 28 are formed to connect pads (notshown) formed on the periphery of the imaging region 24 of the substrate1 and the terminals 22. The wires 28 are preferably formed prior to thebonding of the transparent component 9 because the formation of thewires 28 becomes technically difficult after the transparent component 9is bonded to cover the top surface of the substrate 1.

Then, as shown in FIGS. 4E and 4F, an adhesive layer 10 made of anadhesive such as an epoxy adhesive or an acrylic adhesive is applied tothe top surface of the second transparent layer 8 up to a thickness of0.05 μm or more and 10 μm or less. A transparent component 9, e.g., aglass plate, is then placed on the adhesive layer 10 and the adhesivelayer 10 is cured by heating at 100 to 150° C. to bond the transparentcomponent 9 to the second transparent layer 8. The adhesive layer 10 maybe made of a resin which is cured by both of heating and UV irradiation.FIGS. 4E and 4F correspond to FIG. 3G.

Then, as shown in FIG. 2D, after the formation of the wires 28 and thebonding of the transparent component 9 made of glass, external terminals32 are formed. Thus, the solid state imaging device of the presentembodiment is obtained.

Effect of the Solid State Imaging Device of the Present Embodiment

As described above, according to the method for manufacturing the solidstate imaging device of the present embodiment, the dicing is carriedout in the step shown in FIG. 2C with the second transparent layer 8harder than the first transparent layer 7 exposed. Therefore, scratchescaused by abatement of the substrate 1 are less likely to occur. In thesolid state imaging device of the present embodiment, defects such asblack scratches in the resulting image are prevented from occurring.Further, since a relatively soft resin such as a fluorine-containingresin is used as the first transparent layer 7 on the microlenses 6,stress to be applied to the components of the solid state imaging deviceis absorbed.

The second transparent layer 8 has a refractive index of about 1.3 ormore and 1.6 or less in the present embodiment. If the refractive indexof the first transparent layer 7 is set about 1.4 which is lower thanthat of the microlenses 6, the difference in refractive index betweenthe first and second transparent layer 7 and 8 is reduced, and so is thedifference in refractive index between the second transparent layer 8and the adhesive layer 10. This prevents the reflection of the incidentlight at the interface between the first and second transparent layers 7and 8 and the interface between the second transparent layer 8 and theadhesive layer 10. Therefore, a sufficient amount of light is collectedeven if the light receiving element is reduced in size, therebyproviding the solid state imaging device with high sensitivity.

Further, since the transparent component 9 is directly bonded onto thesolid state imaging element 20 with the adhesive layer 10 interposedtherebetween, the mixing of dust in the package is prevented. Moreover,the total thickness of the device is reduced as compared with theconventional solid state imaging device shown in FIG. 6B.

Thus, the solid state imaging device of the present embodiment, which ishighly sensitive and small-sized, is manufactured with high yield.

Second Embodiment

FIG. 5A is an oblique view illustrating the appearance of a solid stateimaging device of a second embodiment of the present embodiment, FIG. 5Bis a top view of the solid state imaging device and FIG. 5C is asectional view illustrating part of an imaging region of the solid stateimaging device. In FIGS. 5A to 5C, the same components as those of thefirst embodiment shown in FIGS. 1A to 1C are indicated by the samereference numerals to omit the explanation.

As shown in FIG. 5A, a solid state imaging device 46 of the presentembodiment includes a package 26 carrying a solid state imaging element40 therein and external terminals 32 for externally transmitting imagesignals. The solid state imaging element 40 is provided with an imagingregion 24 (a shaded portion in FIG. 5B) where light is received.

As shown in FIGS. 5B and 5C, the solid state imaging device 46 of thepresent embodiment is the same as the solid state imaging device 36 ofthe first embodiment except that a second transparent layer 58 made ofmaterial which is more hydrophilic than the first transparent layer 7 isprovided between the first transparent layer 7 and the adhesive layer10.

The second transparent layer 58 in the solid state imaging device 46 ofthe present embodiment is about 0.05 μm or more and 2.0 μm or less inthickness and may be made of at least one of an acrylic resin, a styreneresin, an epoxy resin and PVA which do not contain fluorine in theirmolecular structures.

The solid state imaging device 46 of the present embodiment ismanufactured by the same method described in the first embodiment. Sincethe second transparent layer 58 is highly hydrophilic, water reacheseasily between the abatement and the second transparent layer 58 duringthe dicing step shown in FIG. 2C, thereby easily washing the abatementaway. Therefore, the scratches are less likely to occur on the topsurface of the second transparent layer 58 and the mixing of theabatement in the package 26 is prevented. Thus, the solid state imagingdevice of the present embodiment is manufactured with high yield. It ismore preferable if the second transparent layer 58 is more hydrophilicand harder than the first transparent layer 7 because the occurrence ofthe scratches is further prevented.

If the first transparent layer 7 is made of a fluorine-containingmaterial, the top surface of the first transparent layer 7 may besubjected to oxygen plasma treatment to make it hydrophilic to someextent. However, according to the inventors' confirmation, the abatementwas not satisfactorily washed away in the absence of the secondtransparent layer 58, the scratches were formed on the first transparentlayer 7 and the abatement remained undesirably on the imaging region 24.However, if the second transparent layer 58 is provided, the occurrenceof the scratches is significantly reduced and the abatement is removedwell. This indicates that the provision of the highly hydrophilic secondtransparent layer 58 is significantly effective.

Thus, as described above, the solid state imaging device and the methodfor manufacturing the same according to the present invention are usefulfor the manufacture of solid state imaging devices for video cameras andthe like.

1-11. (canceled)
 12. A solid state imaging device comprising: a lightreceiving element formed on a semiconductor substrate; a microlensformed on the light receiving element; a first transparent layer formedon the microlens; a second transparent layer formed on the firsttransparent layer; and a third transparent layer formed on the secondtransparent layer, wherein a top surface of the first transparent layeris flat, the first transparent layer has a refractive index lower than arefractive index of the microlens, and second transparent layer isharder than the first transparent layer.
 13. The solid state imagingdevice of claim 12 further comprising: a color filter formed on thelight receiving element and under the microlens.
 14. The solid stateimaging device of claim 12 further comprising: a fourth transparentlayer formed on the second transparent layer and under the thirdtransparent layer.
 15. The solid state imaging device of claim 14,wherein the fourth transparent layer is made of an epoxy adhesive. 16.The solid state imaging device of claim 14, wherein the fourthtransparent layer is made of an acrylic adhesive.
 17. The solid stateimaging device of claim 14, wherein the fourth transparent layer has arefractive index of 1.5 or more and 1.6 or less.
 18. The solid stateimaging device of claim 12, wherein the first transparent layer is madeof a fluorine-containing resin.
 19. The solid state imaging device ofclaim 12, wherein the first transparent layer has a refractive index of1.3 or more and 1.5 or less.
 20. The solid state imaging device of claim12, wherein the second transparent layer is made of material which ismore hydrophilic than the first transparent layer.
 21. The solid stateimaging device of claim 12, wherein the second transparent layer has arefractive index of 1.3 or more and 1.6 or less.
 22. The solid stateimaging device of claim 12, wherein the second transparent layer is madeof a resin containing no fluorine in its molecular structure.